1. Field of the Invention
The apparatus of the present invention relates to valves. More particularly, the present invention relates to a valve which would function as a first out indicator in a system monitoring a number of functions in producing oil and gas wells.
2. General Background
In a producing gas or oil well, it is required that a number of functions which are occurring in the production of gas or oil through the system be monitored so that in the event a malfunction occurs, the precise malfunction can be located, and remedied. There are numerous types of monitors utilized in order to achieve this, one of these monitors, as known in the art, are deemed first out indicators. A first out indicator is normally a pneumatic device which is kept in an open position for allowing gas under pressure to flow through the indicator during operation of the system. The valve is maintained open by pilot pressure, usually on the base of the valve, which is pressurized within a certain range of pressure. Alternately, the device may be of the parallel logic design in which case pilot pressure will maintain the valve in an "in service" position with the system or inlet pressure blocked from the exhaust port, maintaining the system pressure. If the pilot pressure is reduced below the appropriate range, due to a malfunction, the first out indicator will move to the vent position, and that particular system will be shut in. Since the shut in of the production process may produce conditions which would indicate other malfunctions, the first out indicator would indicate that malfunction which had occurred first, prior to the system shut in. This provides information which may be used to remedy the situation which caused the first malfunction and system shut in.
The following patents are noted as being pertinent to the present state of the art:
U.S. Pat. No. 4,660,600 issued to Bergeron, entitled "First Out Indicator" teaches the use of a first out indicator which uses a primary valving means in the valve body for establishing communication between a first fluid inlet and an exhaust means when the valving means is in a first position and blocking the fluid flow when the valve means is in the second or closed position. When the second fluid inlet is pressurized, the fluid from the first fluid inlet causes the valve means to move from the first to the second position. There is also included means which prevents the first valve from moving from the first to the second position which would include a second fluid exhaust means in the housing and means for blocking communication between the first fluid inlet and the second fluid exhaust when the second inlet is pressurized.
U.S. Pat. No. 4,561,464 issued to France, entitled "Relay Valve" provides a relay valve having inlet, outlet and exhaust ports and a gas actuated valving constructed so as to close the exhaust port before the opening of the inlet point.
U.S. Pat. No. 3,901,267 issued to Moon entitled "Relay Construction and Method of Making the Same" which provides a singular relay construction for providing the function of a normally closed relay, a normally opened relay, and a diverting relay so that the single relay construction can be utilized to function selectively as a normally closed relay, as a normally open relay, and as a normally diverting relay.
U.S. Pat. No. 4,559,970 issued to Taylor entitled "Patent Control Relay Valve Apparatus" relates to a pilot relay control valve with a visual indicator. The valve having a main body with a bore extending through the valve having a main slide valve. One end portion extending from the main body to a secondary housing by providing a protectable cover and a means for manually moving the slide valve to a displaced position for setting the controls required in the system.
U.S. Pat. No. Re. 31,845 issued to Peters entitled "Relay Valve for Fluid Actuators" relates to a relay valve having an inlet, outlet, and a pilot pressure port for normally maintaining the valve in the open position. The valve also includes an indicator on the top portion of the valve, which is part of the stem and moves in conjunction with the stem as the stem moves from the open to the close position indicating green and red respectively in the indicator portion of the valve.
U.S. Pat. No. 3,139,902 issued to Thomas; PA1 U.S. Pat. No. 3,129,722 issued to Wagner; PA1 U.S. Pat. No. 3,001,541 issued to St. Claire;
Further patents which are representative of the patents found in the art.